/*
 * Copyright (c) 2012 Robert Burrell Donkin robertburrelldonkin.name
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software 
 * and associated documentation files (the "Software"), to deal in the Software without restriction, 
 * including without limitation the rights to use, copy, modify, merge, publish, distribute, 
 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software 
 * is furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all copies or 
 * substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING 
 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * 
 */
package name.robertburrelldonkin.alfie;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;

public abstract class QueueFedCog<Subject> extends Cog {

	public static final int DEFAULT_TIMEOUT = 100;

	protected abstract void communicate(final Subject subject);

	protected final BlockingQueue<Message<Subject>> in;
	private final int timeoutInMillis;

	public QueueFedCog(BlockingQueue<Message<Subject>> in) {
		this(in, DEFAULT_TIMEOUT);
	}
	
	public QueueFedCog(BlockingQueue<Message<Subject>> in, final int timeoutInMillis) {
		super();
		this.in = in;
		this.timeoutInMillis = timeoutInMillis;
	}
	
	@Override
	protected final void doHook() {
		try {
			if (in.isEmpty()) {
				awaitingInputHook();
			}
			final Message<Subject> message = in.poll(timeoutInMillis, TimeUnit.MILLISECONDS);
			if (message == null) {
				awaitingInputHook();
			} else {
				final Subject subject = message.getSubject();
				switch (message.getEvent()) {
				case COMMUNICATION:
					communicate(subject);
				break;
				case FATAL:
				case STOP:
					finish();
					break;
				}
			}
			afterDoHook();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

	protected void afterDoHook() {}

	protected void awaitingInputHook() {}

}